The Rand Paul pile-on session began a few hours before sunset Sunday evening.

Behind closed doors in the Senate’s Strom Thurmond Room, Republican senators lashed out at the junior Kentucky Republican’s defiant stance to force the expiration of key sections of the PATRIOT Act, a law virtually all of them support. Indiana Sen. Dan Coats’ criticism was perhaps the most biting: He accused the senator of “lying” about the matter in order to raise money for his presidential campaign, according to three people who attended the meeting.

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The message may have gotten through to Paul except for one thing: The libertarian-minded senator skipped the hour-long meeting. That only infuriated his colleagues more.

“Anything that goes against anything he believes, he never comes,” Coats said in an interview. “It’s always helpful if you’re in there working to have your position understood, and we all learn a lot and we all try to come to a much better understanding of what we’re trying to do.”

“He needed to be there,” said Sen. Dean Heller (R-Nev.). “He really needed to be there.”

Sen. John McCain (R-Ariz.) noted that Paul has missed “a number of meetings” Republicans have held on the PATRIOT Act in recent weeks. He contended there was an obvious political reason for Paul’s stance, pointing out how his colleague was tweeting supporters taking “selfies” of themselves next to Paul speaking on TV.

“I know what this is about — I think it’s very clear – this is, to some degree, a fundraising exercise,” McCain said Sunday. “He obviously has a higher priority for his fundraising and political ambitions than for the security of the nation.”

The stinging personal criticism of Paul showed just how unpopular the Kentucky Republican’s demands to kill the surveillance law is among party elders — and portended how this battle is likely to continue to hover over his presidential campaign, for better or worse. It marked the first time in Paul’s brief tenure in Washington where he’s become the scourge of much of his party — not unlike how the party establishment turned on Ted Cruz over his role in the 2013 government shutdown.

Like Cruz, Paul is clearly relishing it.

“Tonight begins the process of ending bulk collection,” Paul said proudly on the Senate floor, just hours before the expiration of key provisions in the law. And in a sign of the ill will between him and his colleagues, Paul took a personal whack of his own.

“People here in town think I’m making a huge mistake,” he said. “Some of them, I think, secretly want there to be an attack on the United States so they can blame it on me.”

Since becoming a senator, Paul has long railed against the PATRIOT Act, arguing it’s a blatant violation of Americans’ constitutional privacy rights. His position gained steam among many civil libertarians after Edward Snowden exposed the National Security Agency’s bulk data collection program of Americans’ phone records.

Buoyed by Snowden’s leaks, a bipartisan majority in the House moved to overhaul the bulk data program through the USA Freedom Act by proposing that phone companies — not the federal government — maintain those records, though the NSA could access them via a secret court order.

But Paul contends that the USA Freedom Act would be an expansion of the PATRIOT Act and could torpedo a lawsuit aimed at ending the bulk data program. The phone companies, he said, “may do the same thing” as the NSA.

Republican leaders in the Senate, after initially resisting the USA Freedom Act because of concerns it would hamper intelligence gathering, on Sunday reluctantly accepted it. They did so with a midnight deadline to extend the surveillance law hours away, their backs against the wall.

That made Paul even more isolated than he was already.

“I think there are some legitimate debates going on in the country over who should hold the documents,” said Sen. Roy Blunt (R-Mo.), a member of GOP leadership and the Senate Select Committee on Intelligence. “I think there aren’t very many people in Sen. Paul’s place that believe that none of these provisions need to be extended or held onto in some way.”

After skipping the GOP meeting, Paul appeared for a tense floor debate between him and his colleagues, including the man who has endorsed him for president: Senate Majority Leader Mitch McConnell, a fellow Kentuckian. The GOP leader was incensed at Paul’s refusal to allow a two-week renewal of far-less controversial provisions of the PATRIOT Act: The use of roving wiretaps for terrorism suspects that change phone numbers quickly and “lone wolf” provisions that allow tracking of suspects who are not affiliated with known terrorist groups.

Just as McConnell attempted to pass a short-term extension, Paul launched into his own impassioned speech— only to be shouted down by his colleagues.

“One of the promises that was given when the PATRIOT Act was originally passed was that in exchange for allowing a less than constitutional standard, we would only use the actions against …” Paul said before he was interrupted by Sen. Roger Wicker (R-Miss.), who pounded his desk while presiding over the Senate.

“Is there objection?” Wicker asked as Paul tried to continue on. A number of Republican senators began yelling over Paul to restore order in the chamber and prevent another lengthy speech.

“I object,” Paul responded. That prompted McConnell to launch his own speech. At times glaring at Paul, the Senate leader blasted what he called “a campaign of demagoguery and disinformation launched in the wake of unlawful actions of Edward Snowden, who was last seen in Russia.” Paul sat at his desk quietly, holding his glasses in his hand.

McConnell never named Paul in his passionate speech, but it was clearly aimed at the man who had been a close political ally — until now.

“I think he’s nestled in with a very large bunch of very radical people – from the left to the right,” said Utah Sen. Orrin Hatch, the president pro tempore. “I don’t know if he feels comfortable being with all those leftists who hate the PATRIOT Act. But he has a right to do what he’s doing.”

Paul ended up delaying a final Senate vote on the USA Freedom Act until later this week. After blocking that bill before the Memorial Day recess, McConnell and GOP leaders agreed to move the House’s measure, saying they had no other choice. By a 77-17 vote Sunday, the Senate broke a filibuster and moved to begin debate on the bill.

To overcome Paul’s delay tactics, McConnell was forced to employ a rarely used prerogative to force senators to debate after a filibuster has been broken, allowing him to move to final passage as early as Tuesday.

As that vote was occurring, Paul was sitting at his desk. He huddled with two libertarian-minded House members: GOP Reps. Justin Amash of Michigan and Thomas Massie of Kentucky. His fellow 2016 rivals, Sens. Ted Cruz of Texas and Marco Rubio of Florida, were yukking it up nearby with a small group of senators. (Rubio voted against proceeding to the House bill, while Cruz supported it.)

In an interview, Amash said Paul’s positions are supported “overwhelmingly” by voters of “all political affiliations.”

“It’s not politically risky to stand with the vast majority of Americans,” Amash said. “I’m astonished when I hear Republican candidates in particular speak as though people want the PATRIOT Act. They don’t.”

“He’s exposing the country to the Constitution,” Massie added. “And the senators that think that’s dangerous are saying the Constitution’s dangerous.”

Rubio called the expiration of the PATRIOT Act’s provisions the result of “political posturing.”

“There are other ways this could have been done,” said Sen. Jeff Flake (R-Ariz.).

One way Paul could have handled the matter would have been to simply object to short-term extensions of current law, rather than giving a nearly 11-hour floor speech on the floor before the Memorial Day recess, Heller said.

“It accomplished just the same, but he couldn’t raise money objecting,” Heller said. “He could only raise money filibustering.”